Abrasive drum for leather surfacing machines and the like



Patented Dec. 27, 1938 UNITED STATES PATENT OFFIE ABRASIVE DRUM FOR LEATHER SURFAC- ING MACHINES AND THE LIKE Claims.

The invention relates to abrasive drums. I

One object of the invention is to provide an improved clamp for holding sheet abrasive material toan abrasive drum. Another object of the invention is to provide an improved construction for separating the heads in a helical path. Another object of the invention is to provide an abrasive drum structure of rigid construction and capable of operating under high speed and considerable pressure without developing vibration or play in any of the parts. Another object of the invention is to provide a simple construction. for abrasive drums of the class indicated which may be manufactured at small cost. Other objects will be in part obvious or in part pointed out hereinafter.

' The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

, In the accompanying drawing showing one of many possible embodiments of the mechanical features of this invention,

Figure 1 is an axial sectional view of the abrasive drum constructed in accordance with the invention;

Figure 2 is an end view;

Figure 3 is an end view of a clamping ring on a small scale;

Figure 4 is a plan View of the abrasive paper before application to the drum.

The abrasive drum of my invention may be used on the type of machine shown in my prior Letters Patent No. 1,983,585 or on the type of machine shown in George M. Curtin Patent No. 2,086,516. The abrasive drum of my invention, however, is not limited to use on such machines but may be used also on wood sanders and other machines where a large cylindrical abrasive surface is desired. Accordingly, it is not believed to be necessary to describe any particular machine, especially as the aforesaid patents may be referred to, as well as George M. Curtin Patent No. 2,076,193 describing an abrasive drum for leather surfacing machines in which abrasive paper is strapped taut on the cylindrical surface thereof. Referring now to Figure 1, there is provided a horizontal shaft 19 constituting the axial shaft for the abrasive drum and which may be journalled in the machine, as shown in my prior patent referred to or as shown in Curtin Patent No. 2,086,516 or in any other suitable manner, and which may be driven in any suitable way, for

example as shown in said patents. I further provide a cylindrical drum H having an outer cylindrical surface broken only by a spiral groove I la in which the abrasive material is overlapped; The drum ll may be made of cast iron or any other suitable material and is preferably an integral structure. The drum H has diametral Web portions i2, i2 which are press fitted into the drum and which have hubs i3, i3 keyed, to the shaft lil by means of keys M. 5

Journalled ineach of the diametral web portions !2 is a stud l5 with which is integrally formed a pinion gear it. The stud l5 extends outwardly and has a square wrench portion ilk Annular webs it having hubs l8 keyed to the shaft it by means of the key it have journals for the outer or long ends of the studs i5 in alignment with the journals in the web i2, thereby effectively and rigidly holding the studs i5 so that great power may be exerted by the pin- 15 ions I6.

The pinions Hi mesh with internal ring gears 2% which are press fitted into externally threaded annular members 2! of stepped shape in cross. section, as shown in Figure l. The ring gear 20 20 fits against a shoulder 22 of the annular threaded member 2! and is to all intents and purposes integral with the annular member 2!. The annular members 2i are free to move in-, side of the drum l5. 25

At each end of the drum I i is a head 25 which consists of an annular outer portion having steps as shown in cross section and having an inwardly extending cylindrical portion 26 which is internally threaded and in threaded engage- 30 ment with the corresponding annular threaded member 2|. Each head 25 likewise has a diametral web 21 fitting around the shaft I!) but not secured thereto. Each head 25 is free to move relative to the drum H. the drum at each end thereof against a shoulder 29 so as to be virtually a part of the drum 5 l is a collar 36 having a series of spiral grooves 3i therein. Spiral grooves 32 extending in the same angular direction are formed in the portions 26 40 of the heads 25 and keys 33 are located in grooves or keyways 3i and 32. As shown, there are four grooves 3! in each collar 3!! and four grooves 32 in each inward extension 25 of each head 25 and there is a key 33 between each pair of grooves 3i and 32, there thus being eight keys in all. The key 33 may be tight in either of the grooves 3! and loose in the other one, as desired.

There is an arcuate slot 35 in each of the websv 0 2'! through which an end wrench may be inserted, thereby to turn either of the studs l5 and with it its corresponding pinion gear It. This action turns corresponding annular threaded portion 2! which moves the corresponding head 21 55 either inwardly or outwardly, depending on the direction which the stud I5 is turned. The head 25 in question, however, can only move outwardly in a spiral course as determined by the pitch of the grooves 35 and 32 and the keys 33 therein. 60

Press fitted into 35 plane of the axesof all the bolts 38.

This pitch is the same as the pitch of the abrasive paper upon the drum I I.

Extending outwardly from each head is an annular cylindrical portion 36 which is an integral part of head 25. In this outwardly extending cylindrical portion are a plurality of slots 31 large enough to receive a plurality of bolts 38 having heads 39 with sockets 4!! for internal end wrenches. Square nuts 4| abut the web vZIand thus the bolts 38 may readily be tightened. Bolts 38 extend through holes in a.clamp.42, the heads 39 seating in countersunk portions thereof, as shown. The clamp 42'maybemade of steel and in cross section is shaped as clearly shown in Figure 1 with a paper clamping portion 43 and an outer and inwardlyextendingannular portion 44 which abuts-the. outer cylindrical surface of the cylindricalextension 36, thereby to -exert the thrust of the bolts 38 against the cylindrical portion 36-so that the reacting'force will tightly clamp the clamp portion- 43 againstthe paper 45. It will be seenthat each part of the clamp 42 acts as -a lever and in order that clamping action may beeffected, saw cuts 46 and 41 are made in the clamps 42, the saw cuts 46 beingon the outside and the saw cuts 41 on the inside and each one extending approximately to the -median line of the clamp or-about to the These saw cuts arepreferably in staggered relation. Thus the clamping rings 42 are integral one piece rings but nevertheless the clamping action may be freely exerted. By reason of the fact that they are flexed inwardly at the several bolts but consist of integral pieces, they follow the contour of the cylindrical surface of the drum I I very closely and clamp the paper 45..verysmoothly thereto.

The paper 45 extends betweenthe clamps and is laid upon thedrum II in a helical course and overlapped in the groove IIa. Figure 4 shows the shape of theabrasivepaper before it. is'ap- .pliedto the drum. With the clamps herein disclosed, the paper can be held very tightly to the heads 25 and with the .mechanism for moving the heads outwardly in. a helical course, the paper can be madevery taut and-all wrinkles removed. The-.threads inthe annular .members 12 I .andthe .heads 36 are self-lockingso that oncethe paper is tightened, the parts will not move excepting by the further applicationof a wrench to theends I! .of the .studs I-5.

'It will thus be seen that there has been provided by this invention an apparatus in which the various objects hereinbeforeset forth together with many'thoroughly practical advantages aresuccessfully achieved. As many possible embodiments may be made in the mechanical features of the above invention and as many changes may be made in the embodiment set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawing is to be interpretedas illustrative and ;not'in a limiting sense.

I claim: 1. An abrasive drum construction comprising a metal cylindrical shell, a pair of heads one on each end of .saidshell, each head comprising a peripheral portion flush with the exterior of said shelland a. shouldered portion fitting under said shell and the heads being rotatably mounted with respectto said shell,. 2. central mounting shaft for thedrum, hubs mounted on and fastened to said central shaft, studs journalled in said hubs, pinion gears on-saidstuds,ring-gearsoutside of andimeshing with said ;pinion gears,. inwardly extending cylindrical flangesv integral with said heads, annular members inside of 1 said inwardly extending cylindrical portions but outside of said studs, said annular members being threadedzon the outside and in engagement with. threads on the flanges, the internal gears being fastenedito the annular members, and spiral .directingrmeans connecting the flanges and the drum whereby upon turning the studs the heads are 'moved spirally outwardly.

2. An abrasive drum construction comprisingsa metal cylindrical shell, means including .a spiral slot on the inside of said shell, ahead rotatably mounted on said shell having an internal annular portion inside of said means and a peripheral-portion, cooperating spiral grooved means on the outside of said annular portion, whereby the head isforced to move spirally with respect .to the spiral groove means, and the thrustbeingclose to the spiral groove and spiralgroove means.

3. In apparatus asclaimed in .claim 1, the com- .bination with the parts and features therein specified of annular clampshaving portions .to 1 engage the peripheries of the heads, and .tbolt means to press the-clamps inwardlyagainstthe heads, there being cuts in the clamps to permit them to flex inwardly.

.4. In, apparatus asclaimed in claim-2, the. combination with the parts .and features therein specified, otan annularclamp having aportion to. engage the periphery of the head, there. being cuts inthe clampto permit it to be flexed.in-

wardly, and radial bolts secured-to the headand passing through the clamp to .clamp 1a; piece of coated abrasive. materialonto the head andthereby position it on.the drum.

5. A, clamp for an abrasive drum comprising a ring having a portion withan-internal cylindrical surfaceto effect the clamping.holesinsaid. ring on the edge of said portion, bolts extending throughsaid holes radially of the ring,.and.cuts on either side of the ring to.permit it'tolbe 'flexed inwardly.

EDGARH. VAN .VALKENBURGH, 

